Salyut 1 originated as a modification of the military "Almaz space station program then in development. After the landing of "Apollo 11 on the Moon in July 1969, the Soviets began shifting the primary emphasis of their manned space program to orbiting space stations, with a possible lunar landing later in the 1970s if the N-1 booster became flight-worthy (it did not). One other motivation for the space station program was a desire to one-up the US "Skylab program then in development. The basic structure of Salyut 1 was adapted from the Almaz with a few modifications and would form the basis of all Soviet space stations through "Mir.

Civilian Soviet space stations were internally referred to as "DOS" stations, although publicly, the Salyut name was used for all Almaz and DOS stations. Several military experiments were nonetheless carried on Salyut 1, including the OD-4 optical visual ranger, the Orion ultraviolet instrument for characterizing rocket exhaust plumes, and the highly classified Svinets radiometer.

Construction of Salyut 1 began in early 1970, and after nearly a year it was shipped to the Baikonur Cosmodrome. Some remaining assembly work had yet to be done and this was completed at the launch center. The Salyut programme was managed by "Kerim Kerimov,[1] chairman of the state commission for Soyuz missions.[2]

Launch was planned for April 12, 1971 to coincide with the 10th anniversary of "Yuri Gagarin's flight on "Vostok 1, but technical problems delayed it until the 19th. The first crew launched later in the "Soyuz 10 mission, but they ran into troubles while docking and were unable to enter the station; the Soyuz 10 mission was aborted and the crew returned safely to Earth. A replacement crew launched in "Soyuz 11 and remained on board for 23 days. This was the first time in the history of spaceflight that a space station had been manned, and a new record time was set in space. This success was, however, short-lived when the crew was killed during re-entry, as a pressure-equalization valve in the Soyuz 11 re-entry capsule had opened prematurely, causing the crew to asphyxiate. After this accident, all missions were suspended while the Soyuz spacecraft was redesigned. The station was intentionally destroyed by "de-orbiting after six months in orbit, because it ran out of fuel before a redesigned Soyuz spacecraft could be launched to it.[3]

At launch, the announced purpose of Salyut was to test the elements of the systems of a space station and to conduct scientific research and experiments. The craft was described as being 20 m (66 ft) in length, 4 m (13 ft) in maximum diameter, and 99 m3 (3,500 cu ft) in interior space with an on-orbit dry mass of 18,425 kg (40,620 lb). Of its several compartments, three were pressurized (100 m³ total), and two could be entered by the crew.[4]

The transfer compartment was equipped with the only "docking port of Salyut 1, which allowed one "Soyuz 7K-OKS spacecraft to dock. It was the first use of the Soviet "probe and drogue" type docking system that allowed internal crew transfer, a system that is in use today. The docking cone had a 2 m (6.6 ft) front diameter and a 3 m (9.8 ft) aft diameter.[4]

The second, and main, compartment was about 4 m (13 ft) in diameter. Televised views showed enough space for eight big chairs (seven at work consoles), several control panels, and 20 portholes (some obstructed by instruments).[4]

The third pressurized compartment contained the control and communications equipment, the power supply, the "life support system, and other auxiliary equipment. The fourth, and final, unpressurized compartment was about 2 m in diameter and contained the engine installations and associated control equipment. Salyut had buffer chemical batteries, reserve supplies of oxygen and water, and regeneration systems. Externally mounted were two double sets of "solar cell panels that extended like wings from the smaller compartments at each end, the heat regulation system's "radiators, and orientation and control devices.[4]

Salyut 1 was modified from one of the "Almaz airframes. The unpressurized service module was the modified service module of a Soyuz craft.

After taking 24 h for rendezvous and approach, "Soyuz 10 soft-docked with Salyut on April 23[3] and remained for 5.5 h. Hard-docking was unsuccessful due to an unforeseen design flaw in the Soyuz's autopilot. The crew could not enter the station and had to abort the mission.

Studying physical characteristics, processes, and phenomena in the atmosphere and outer space in various regions of the electromagnetic spectrum, and

Conducting medico-biological studies to determine the feasibility of having cosmonauts in the station perform various tasks, and studying the influence of space flight on the human organism.

On June 29, after 23 days and flying 362 orbits, the mission was cut short due to problems aboard the station, including an electrical fire. The crew transferred back to Soyuz 11 and reentered the Earth's atmosphere. The capsule parachuted to a soft landing in Kazakhstan, but the recovery team opened the hatch to find all three crew members dead in their couches. An inquest found that a pressure relief valve had malfunctioned during re-entry leading to a loss of cabin atmosphere. Pressure suits had not been used on Soviet manned spacecraft since the "Vostok program.[6]

Salyut 1 was moved to a higher orbit in July–August 1971 to ensure that it would not be destroyed prematurely through "orbital decay. In the meantime, Soyuz capsules were being substantially re-designed to allow pressure suits to be worn during launch, docking maneuvers, and re-entry.[6] The Soyuz redesign effort took too long however, and by September, Salyut 1 was running low on "attitude control gas. It was decided to conclude the station's mission and on October 11, the main engines were fired for a deorbit maneuver. After 175 days, the world's first space station burned up over the "Pacific Ocean.

"Pravda (October 26, 1971) reported that 75% of Salyut 1's studies were carried out by optical means and 20% by radio-technical means, while the remainder involved magnetometrical, gravitational, or other measurements. Synoptic readings were taken in both the visible and invisible parts of the "electromagnetic spectrum.[4]